Modern automobile body shapes are distinguished by relatively large window areas. Because of strong sunlight, the large window areas result in considerable heat generation in the interior of the vehicle and, in connection with vehicles with air conditioning, this major heat generation results in a not inconsiderable use of energy in order to counteract the heating effects on the vehicle.
For this reason, motor vehicles are increasingly equipped with windup window shades.
In connection with this it is known to attach two guide rails laterally next to the window, in which the end of the traction rod of the window shade web is guided. The length of the traction rod is adjustable in order to be able to accommodate various window widths. Actuation takes place by means of the thrust members running in the guide rails.
Only two states are possible here, too, namely the unhampered entry of light or a reduction in accordance with the reduction effects of the windup shade web.
Based on the foregoing it is the object of the invention to create a windup window shade for motor vehicles, which allows a total of three operational states and has a simple drive mechanism.
In accordance with the invention, this object generally is achieved by a windup window shade for regulating the entry of light through a window into the interior of a motor vehicle, in particular a rear window windup shade, comprising: a first windup shaft, that is rotatably seated; a second windup shaft that is seated axially parallel and adjoining the first windup shaft, a first window shade web, one edge of which is fastened on the first windup shaft, and whose other edge, which is parallel with the on edge latter, is connected with a first traction rod; a second window shade web, one edge of which is fastened on the second windup shaft, and whose other edge, which is parallel with the one edge, is connected with a second traction rod; and a pair of guide means, each of which extends laterally next to the extended window shade webs. Additionally, the windup window shade includes a drive mechanism that only has a first and a second thrust member, and that is arranged such that one end of the first thrust member, selectively engages, i.e. acts together with, the one end of the first traction rod, and the other end of the first thrust member acts together with, i.e., selectively engages, the one end of the second traction rod, and such that one end of the second thrust member selectively engages the other end of the first traction rod, and the other end of the second thrust member selectively engages the other end of the second traction rod, and wherein in one position of the two thrust members none of the two window shade webs is extended.
The windup window shade in accordance with the invention has two window shade webs which, however, can be extended selectively, but not at the same time. Because of this, a total of three states is possible, in which the light entering through the respective window is differently affected.
Although there are two separate window shade webs, only a single drive motor is needed for them in the end. Use is made of the fact that the thrust members move in opposite directions for actuating the traction rods. By means of an appropriate cross coupling it is possible to extend one or the other window shade web with the aid of the same pair of thrust members.
Here, the reduction in the number of drive motors has a considerable economical importance. The reduction of the number to only a single motor leads to considerable cost reductions, because the gear motor represents an important cost factor in connection with such a windup window shade. Moreover, the space requirements are considerably reduced. The arrangement can be installed in spaces which sometimes might not offer sufficient space for two motors.
If the thrust members drive the traction rods by cross-coupling in such a way, that the ends of the same thrust member respectively actuate the ends of the two traction rods which are farther distanced from each other, tight radii of curvature and unnecessary lengths are avoided.
The actuation of the windup shafts and synchronization with the electrical drive mechanism of the traction rods becomes particularly simple when each of the windup shafts has its own spring drive, by means of which it is biased in the direction of the windup of the respective window shade web. The varied settings for the entry of light can be achieved if one of the window shade webs only slightly reduces the entry of light, so that a view through the extended window shade web is still possible. Such a window shade web preferably consists of a wide-mesh woven material, or of a perforated and dark-colored foil.
In contrast to this, the other window shade web can prevent the entry of light to a much larger degree if, for example, it is only used in a parked vehicle. In this case it is advantageous to design the window shade web in such a way that it prevents heating up of the vehicle interior to the best possible extent. Window shade webs coated with a reflecting material are particularly useful for this.
Moreover, the window shade web which is completely opaque offers a visual protection for the parked vehicle.
Windows are often not rectangular because of the shape of the vehicle body and other reasons of design.
As a rule, they have a more or less extensive trapezoidal shape. So that the traction rods can follow this shape, their shape can preferably be adjusted in length.
Assembly of the windup window shades in accordance with the invention is simplified, if the guide grooves which more closely adjoin each other are embodied in a common guide rail.
So that the length adjustment of the traction rods can also be performed without the aid of springs, the guide grooves are preferably undercut guide grooves in order to be able to generate with the aid of the guide grooves a force, by means of which the traction rod is longitudinally pulled.
The thrust members are flexible linearly shaped thrust members which are preferably mainly dynamically balanced. The tendency to rotate in curved sections, in which the thrust members are guided fixed against kinking, is counteracted by means of this.
The thrust members are comparatively easy to bend and because of this they are guided, safe from kinking, between the guide groove and the gear motor.
The thrust members preferably consist of an essentially cylindrical core, on the exterior of which teeth are formed. These teeth can be constituted by one or several helically extending ribs. In this way it is possible for the thrust members to act together interlockingly with the gear motor.
Since there is the danger, in particular with the dual drive mechanism in accordance with the invention, that the respective traction rod is not moved exactly parallel in relation to the respective windup shaft by the thrust members, it is practical to seat the windup shafts floatingly. In this way they can adjust themselves parallel with the traction rod by means of the action of their being biased in the respective window shade web. The appearance of folds, which otherwise would occur, is dependably prevented.
Further embodiments of the invention are inter alia subject of dependent claims. It is intended here that also those combinations of characteristics are considered to be claimed, for which there is no explicit exemplary embodiments.